To be honest i don't use Eclipse myself as i got many troubles making it working with SGDK.
Still from your messages log, did you correctly defines GDK environment variable and custom build command ?
You GDK var should be set to :

It looks like you used '\' (windows path separator)instead of '/' (linux path separator).
Even if you are on windows you need to use '/' as windows now support it, and mixing them will probably screw up everything.

Also you might try to define "GDK_WIN" environment variable which should point to your SGDK installation path but in windows format

it had to be saved in order to work the int Main() - now my setup is complete and working without any issues, that means I can try out many SGSK tutorials and maybe build a game or two for the genesis and have the power of 16-bit in my hands!